The present invention relates to a device for the automatic regulation or setting of the push rods of a stamping press. It also relates to a process for using this device.
Hydraulic stamping presses make it possible to stamp hollow parts from metal blanks. Such a press comprises a frame, a table to which is fixed the die and a main slide which moves in translation with respect to the table along the slideways. This slide carries a punch, whose shape is complementary to that of the impression of the die. Shaping, without metal removal, is brought about in equipment not forming part of the machine. The closing, operation and opening of the equipment at the requested shaping pressure takes place by means of a hydraulic cylinder.
A blank holder positioned between the table and the main slide keeps the sheet metal blank locked against the die during the stamping operation. The blank holder also moves in translation with respect to the table in order to supply the press with parts to be stamped and in order to remove the stamped parts.
The necessary clamping force exerted on the blank holder by a blank holder slide located above the main slide is transmitted by push rods. These push rods are in the form of elongated rods traversing the main slide and whose upper end is supported beneath the blank holder slide and whose lower end is supported on the actual blank holder. Transverse ring members are located in the push rods to prevent them from dropping during the outward movement of the main slide during the setting or regulating phases. The upward return of the blank holder is ensured by the main slide using tie bolts which pass through the latter. The lower end of each tie bolt is screwed to the blank holder and is supported by a shoulder of the upper end thereof on the main slide.
In the case of a press of this type, it is necessary to regulate the push rods prior to any stamping of a new series of parts. However, the setting operations take a long time, namely about 2 hours, so that these very expensive machines have to be stopped, which increases production costs. Moreover, these operations are irksome to the operator due to the number and weight of the push rods to be manipulated.
Therefore, considerable interest is attached to reducing the duration of the push rod setting operation. This is the problem solved by the present invention.